Take a Hollywood actress, pair her with a credible theatre production and you have a match made in box office heaven. Throw in a little nudity, and the combination becomes what one critic – talking about Nicole Kidman in The Blue Room – famously described as "theatrical Viagra".
It also has fairly miraculous effects on the box office: big-name stars drew record crowds to London theatres last year. According to the Society of London Theatre (Solt), attendance at plays and musicals reached nearly 14 million in 2008. Box office takings were up by £10m to £480m. So far this year they are up on last year's figures, and advance sales in the West End are approaching £50m. Last month the Ambassador Theatre Group announced that it was expanding and creating 16 new theatres and playhouses at a cost of £90m.
The winning formula was being applied again last night, with Keira Knightley making her much-anticipated West End debut in an updated version of Molière's The Misanthrope. The production took more than £1m in ticket sales in four days. Knightley is one of a growing number of female film stars to tread the boards, among them Cate Blanchett, Sienna Miller and Kidman. While Hollywood's top names usually spell commercial success for a play, critical approval is harder to come by, film actresses almost invariably being panned for delivering below-par stage performances.
"Their names above the door sell tickets, but in the vast majority of cases if they aren't good enough they will be found out," said Paul James, commercial manager of Solt. "However, it is a false idea that Hollywood actors are taking the place of unknowns who would be better at it; without someone of that calibre on board, the show wouldn't be happening, as it'd be too much of a risk."
Although better known for blockbusters such as Pirates of the Caribbean and Atonement, Knightley shouldn't find the role too challenging: she plays a beautiful, young American film star in London, opposite Damian Lewis.